Impact of FMR1 Pre-Mutation Status on Blastocyst Development in Patients Undergoing Pre-Implantation Genetic Diagnosis.

BACKGROUND/AIMS: The study aimed to investigate the impact of fragile X mental retardation 1 (FMR1) pre-mutation status on blastocyst development in patients undergoing pre-implantation genetic diagnosis (PGD).

METHODS

Case-control study of patients <40 years undergoing PGD at blastocyst stage for FMR1 pre-mutation status. Age-matched patients undergoing PGD for other single gene disorders were considered controls. Blastocyst development, calculated per metaphase II (MII) oocyte retrieved and per 2 pronuclear (2PN) embryos, was compared between the 2 groups. Pregnancy outcomes after embryo transfer were also compared.

RESULTS

Eighty-one and 791 patients were included in the FMR1 and control groups, respectively. FMR1 pre-mutation carriers had lower indicators of ovarian reserve, required higher gonadotropin doses, and had fewer MII oocytes retrieved. Mean blastocyst development per MII oocyte (12.6 vs. 29.4%; p < 0.001) and per 2PN embryos (21.5 vs. 41.7%; p < 0.001) was lower in the FMR1 group. An inverse correlation between the number of FMR1 CGG repeats and blastocyst development per MII oocyte (ρ = -0.63; p < 0.001) was observed. There was no difference in the rates of clinical pregnancy, spontaneous abortion, or live birth among the groups.

CONCLUSION

Our study suggests lower rates of blastocyst development in patients with FMR1 pre-mutation status and an inverse correlation between the number of FMR1 CGG repeats and blastocyst development.